The present invention relates generally to snowmobiles. More particularly, the present invention relates to the human-to-machine interface of a snowmobile.
Since their development in the middle of the 20th century, snowmobiles have gained widespread popularity. Snowmobiles are commonly used for trail riding and utility applications Perhaps the most common snowmobile application is recreational trail riding. Trail riding on a snowmobile allows a snowmobile enthusiast to travel through areas which are not accessible by other types of vehicles. For example, snowmobiles can travel very rapidly across frozen lakes during the winter in northern climates. Modem snowmobiles, can cover ground very rapidly and can cover great distances. Frequently, snowmobile enthusiasts ride their snowmobile for many hours straight and cover many miles.
A rider operates a snowmobile by providing inputs such as acceleration inputs provided using a throttle, deceleration inputs provided using a brake, and steering inputs provided using a set of handle bars. The rider may also influence the performance of the machine by shifting his or her weight, for example, by leaning into a turn. Frequently, people become interested in snowmobiling because of the unique riding experience that snowmobiles provide. Part of the thrill of riding a snowmobile is encountering challenging terrain, and traversing that terrain through a combination of the skill of the rider and the way that the snowmobile reacts to the inputs provided by the rider. Aspects of a snowmobile such as the overall weight of the snowmobile, the weight distribution of the snowmobile, and the location of the snowmobile center of gravity all effect the riding experience enjoyed by a snowmobiling enthusiast.
The ability of a rider to traverse challenging terrain smoothly and quickly frequently depends upon the way that the snowmobile responds to the rider. As mentioned previously, the rider can control the snowmobile by providing inputs using the handle bar, brake and throttle. The rider can also control the snowmobile by selectively shifting his or her weight.
The way that a particular snowmobile responds to inputs provided by a rider may depend upon the snowmobile's total inertia, the snowmobile's moment of inertia, and the location of the snowmobile's center of gravity. The total inertia of a snowmobile has an effect on that snowmobile's performance because this total inertia determines the extent to which the snowmobile will resist changes in location and linear velocity. For example, the inertia of an overly heavy snowmobile may limit how rapidly that snowmobile can accelerate and decelerate. The moment of inertia of a snowmobile also has an effect on that snowmobile's performance, since it determines the extent to which the snowmobile will resists changes in angular position and rotational velocity. The moment of inertia of a snowmobile is determine, at least in part by the total mass of the snowmobile the way in which that mass is distributed.
The present invention relates generally to snowmobiles providing an enhanced riding experience. More particularly, the present invention relates to the human-to-machine interface of a snowmobile. A snowmobile in accordance with the present invention may include a frame defining a tunnel and a drive track rotatably supported within the tunnel. The snowmobile may also include an engine connected to the frame and operatively coupled to the drive track by a drivetrain.
A seat may be fixed to the frame for receiving a rider of the snowmobile. A pair of handle bars may be rotatably coupled to the frame and adapted to receive the hands of the rider.
A pair of floor boards may be fixed to the frame and adapted to receive the feet of the rider. In some embodiments, the floor boards include toe stops.
In one aspect of the invention, the engine includes a cylinder bore having a cylinder bore axis that is directed rearwardly and upwardly so that a center of mass of the engine is disposed rearward of a center of rotation of a crank shaft of the engine. Placing the engine in this position may provide a snowmobile having a lower polar moment of inertia compared to a snowmobile having an engine with a center of mass positioned directly above, or in front of the rotational center of the crankshaft.
The engine of the snowmobile has a first side extending in a first direction from the cylinder bore axis and a second side extending in a second direction from the cylinder bore axis.
In one advantageous aspect of the present invention, air may enter the cylinder bore from the first side of the engine, and exhaust gases may exit the engine from the same side. In some applications, this arrangement may facilitating placing the fuel tank in close proximity to the cylinder of the engine.
In still another aspect of the present invention, the fuel tank has a front wall that is generally sloped rearwardly and upwardly. In some implementations of the present invention, the sloped wall of the snowmobile is generally parallel to the cylinder bore axis of the engine. In some implementations, the fuel tank and the engine may be positioned in such close proximity to one another, that a lateral reference plane passing through the snowmobile intersects both the fuel tank and the cylinder of the engine.
In an additional aspect of the invention, a starter of the snowmobile is disposed between the engine and the centroid of the snowmobile. Placing the starter in this position provides a snowmobile having a lower polar moment of inertia compared to a snowmobile having the starter disposed on a front side of the engine.
A snowmobile in accordance with the present invention may comprise a chassis, a shell fixed to a front portion the chassis and extending away from the chassis in a forward direction, and an engine coupled to the chassis for propelling the snowmobile. In some implementations, the shell defines a chamber fluidly communicating with the engine via a flexible coupling interposed between the shell and the engine.
In some implementations, the snowmobile also includes at least one ski coupled to the chassis by a suspension so that the ski is pivotable about a steering axis. In these implementations, the shell may be advantageously disposed forward of the steering axis.
In some implementations, the snowmobile includes a hood that is rotatably supported by the shell. In these implementations, a plenum defined by the hood advantageously fluidly communicates with the chamber defined by the shell at least when the hood is in a closed position. In some implementations, the chamber defined by the shell may be accessed via an opening in the shell when the hood is in the open position.